CN100456522C - Full-wavelength white-light organic electroluminescent device and manufacturing method thereof - Google Patents

Abstract

The invention discloses a full-wavelength white light organic electroluminescent device, which is mainly characterized in that a hole transfer layer, a luminescent layer, a hole blocking layer, an electron transfer layer and an electron injection layer are arranged between a corresponding transparent conductive substrate as an anode and a cathode, wherein the luminescent layer is a luminescent layer which is formed by a blue light material containing a green light dye which is a luminescent main material; the hole blocking layer is doped with red dye of a luminescent main material, so that the hole blocking layer is a hole blocking layer capable of emitting a red light source; therefore, a full-wavelength white light emitting device with large doping concentration and slight concentration change, which does not affect light color and can emit a light with uniform intensity when the wavelength is 450nm to 630nm, can be manufactured.

Description

Full-wavelength white light organic electroluminescence device and manufacturing method thereof

technical field

The present invention relates to a full-wavelength white light organic electroluminescent device, in particular to a full-wavelength white light organic electroluminescent device that can balance and reconcile various colors of light to emit mixed white light, and the white light can be matched with a color filter to make a full-color panel .

Background technique

Organic light-emitting diode (OLED) can also be called organic electroluminescence (OEL for short). Simply put, it is to apply a bias voltage to make electron holes pass through the hole transport layer (Hole Transporting Layer) and the electron transport layer (Electron Transporting Layer) respectively. After transporting Layer), it enters an organic light-emitting layer with light-emitting properties, and forms an "exciton" (exciton) when it is recombined in it, and then releases the energy and returns to the ground state (ground state), and these The released energy will excite the fluorescent molecules in the organic material to generate "photons". Due to the different materials of the selected light-emitting layer, the energy can be released in the form of light of different colors to form the light-emitting phenomenon of OLED .

Organic electroluminescent display technology has become an excellent flat-panel display technology due to its low cost, long life, low driving voltage, fast response speed, good luminous efficiency, good shock resistance, wide viewing angle, and thin thickness. The production of organic EL (Electroluminescence) displays can be achieved by combining organic EL that emits white light with color filters. However, it is not easy to find and match materials for the light-emitting layer that emits white light.

At present, the general method of manufacturing full-color organic electroluminescent displays is to use a shadow mask to position and emit red (R), green (G), and blue (B) three primary colors in parallel. Three photosensitive coupling device (CCD) alignment. However, with the development of high-resolution displays, limited by shielding technology and alignment errors, it is difficult to increase the pass rate of products. In addition, OLEDs with different colors have different structural designs, which is very time-consuming in the manufacturing process; at the same time, OLEDs have different lifetimes for the light-emitting layers that emit red, green, and blue primary colors. Therefore, when one of the light-emitting layers decays, the overall color shift of the display will be serious, making the stability of the product difficult to control.

Therefore, in view of the above shortcomings, it is proposed to use a single white light-emitting element to form a full-color display after matching with a color filter, because a single white light-emitting element does not require alignment of photosensitive coupling elements and uses shielding to define red and green light. , The position of the luminous body of the blue light, so it can effectively reduce the process error, which is of great help to the improvement of the pass rate, and the process time is also reduced by three times compared with the traditional method.

At present, in order to obtain white light-emitting organic electroluminescent elements, it is necessary to excite more than one molecular material, because a single organic molecule cannot easily span the entire visible light spectrum region. One of the ways to achieve white light emission according to the characteristics covering the spectrum is to dope a host emitter with another guest emitter, which can cause energy transfer or carrier capture from the host emitter to the guest emitter at the doping position. Set, incomplete energy transfer can make both emit light at the same time.

It is mentioned in the existing patent "Organic Light-Emitting Device Capable of Projecting White Light Source and Its Manufacturing Method" (please refer to FIG. 1 ) that a hole injection layer 11 is provided between a corresponding anode 10 and a cathode 15, A hole transport layer 12, a light emitting layer 13, and an electron transport layer 14, wherein the light emitting layer (DPVBi) 13 is doped with a first dopant (DCM2), and the electron transport layer 14 is doped with a second dopant (C6), when the cathode 15 and the anode 10 are subjected to an applied voltage, the light-emitting layer 13, the first dopant, and the second dopant can individually project a corresponding third light source (B), the first The light source (R) and the second light source (G) obtain a continuous full-band white light source through the combination of the three primary colors of red, green and blue.

The patent pointed out that the optimal structure is DPVBi doped with 0.025% DCM2, and Alq doped with 0.1% C6. The energy level diagram of the element is shown in Figure 2, where E _XC represents the vacuum energy level and the XC element conduction energy level (X is 10~15 element code) energy level difference, also represents the electron affinity (electron affinities) of the element; E _XV represents the vacuum energy level and the XV element valence band energy level (X is the energy level of the 10~15 element code) Poor, which also represents the ionization potential of the component. It can be seen from the above and the figure that the host material is doped with the guest material. The doping concentration of the guest material is almost less than 1%, and some are even less than 0.1%. It is extremely difficult to control the process parameters, so as long as there is a little The change of the concentration percentage is a drastic change, and it is difficult to make the two light-emitting regions emit light evenly in the design of the double-emitting layer. Often the energy levels of the two light-emitting layers are too close. With the increase of the operating voltage Change, the light-emitting area is also easy to shift with the voltage movement. Moreover, the luminescent spectrum is seriously insufficient in the long wavelength part (as shown in FIG. 3 ), and the intensities of the three primary colors of red, green and blue are very different.

Contents of the invention

The main purpose of the present invention is to solve the above-mentioned deficiency. Therefore, the present invention proposes a full-wavelength white light organic electroluminescence device in which a light-emitting host material is doped in another light-emitting host material. Because the same host material is used, its luminous efficiency is relatively high At the same time, the doping concentration ratio is required to be higher, and the process control becomes easier.

Another object of the present invention is to provide a hole blocking layer. Using the difference in energy levels between the hole blocking layer and the first light-emitting layer, the recombination region of electrons and holes can be limited to the region of the light-emitting host material and the hole. The interface of the hole barrier layer prevents the luminous spectrum of the luminescent region from greatly changing as the voltage changes.

Another object of the present invention is to dope the hole blocking layer with a luminescent dye, so that the hole blocking layer has both the functions of the hole blocking layer and the light emitting layer, so that an organic electroluminescent device that emits white light can be produced.

The present invention is a full-wavelength white light organic electroluminescence device, and its structure includes from bottom to top: a transparent conductive substrate, a hole transfer layer, a light-emitting layer, a hole blocking layer, an electron transfer layer, an electron Injection layer and cathode, wherein the light-emitting layer is a light-emitting layer that emits a blue-green light source formed by a blue light material doped with a green light dye, and the hole blocking layer (34) is doped with a red light dye to make it emit red light. Light source: through the structural design of the device of the present invention, and then selecting an appropriate combination of light-emitting main materials, a full-wavelength white organic electroluminescent element suitable for making a full-color panel with a color filter can be produced.

Description of drawings

FIG. 1 is a schematic diagram of an organic light-emitting device in the prior art.

Fig. 2 is a schematic diagram of the energy levels of each element of the device shown in Fig. 1 .

Fig. 3 is a comparison diagram of wavelength versus luminous intensity of the device according to Fig. 1 .

FIG. 4 is a schematic diagram of an organic light emitting device according to the present invention.

Fig. 5 is a schematic diagram of energy levels of each element of an embodiment of the device according to the present invention.

FIG. 6 is a comparison diagram of the wavelength of the excellent light emitted according to the embodiment of the present invention versus the luminous intensity.

7 is a schematic diagram of coordinates of white light emitted at voltages of 10, 11, 12, 13 and 14V on a chromaticity coordinate diagram (CIE) according to an embodiment of the present invention.

Detailed ways

Relevant detailed content and technical description of the present invention, now in conjunction with accompanying drawing, explain as follows:

Please refer to FIG. 4 , which is a schematic diagram of an organic light-emitting device according to the present invention. As shown in the figure: the structure of the full-wavelength white organic electroluminescent device of the present invention includes from bottom to top: a transparent conductive substrate 31 as an anode, a hole transport layer 32, a light emitting layer 33, and a hole blocking layer 34. An electron transport layer 35, an electron injection layer 36, and a cathode 37, wherein the light-emitting layer 33 is made of a blue light-emitting host material doped with a green light dye 333 of another green light-emitting host material A light-emitting layer 33 emitting blue-green light is formed; at the same time, the hole blocking layer 34 is doped with red dye 344 which is a host material emitting red light, so that the hole blocking layer 34 can emit red light.

The manufacturing method is mainly to provide a hole transfer layer 32, a luminescent layer 33, a hole blocking layer 34, an electron transfer layer 35, and an electron injection layer 36 between a corresponding transparent conductive substrate 31 as an anode and a cathode 37. .

Wherein the light-emitting layer 33 is formed by a blue-light material containing a green light dye 333 which is also a light-emitting host material. The light-emitting layer 33 emits a blue-green light source; 344, making the hole blocking layer 34 a hole blocking layer 34 capable of emitting a red light source; through the combination of the blue-green light source and the red light source, a white light source is formed. In this way, a three-wavelength full-wavelength white organic electroluminescent device with similar luminous intensity can be produced. This full-wavelength white organic electroluminescent device is very suitable for making a full-color display with a color filter.

(例如：日本出光兴产株式会社制造的高亮度蓝光主体材料，编号为Ide120)、二(2-甲基-8-喹啉)4-羟基联苯基铝(bis(2-methyl-8-quinolinato)4-phenylphenolate aluminum(Balq))、聚乙烯基咔唑(Poly(N-vinylcarbazole))(PVK)或4-{4-[N-(1-萘基)-N-苯基氨基苯基]}-1，7-二苯基-3，5-二甲基-1，7-二氢-二吡唑并[3，4-b；4’3’-e]吡啶(4-{4-[N-(1-naphthyl)-N-phenylaminophenyl]}-1，7-diphenyl-3，5-dimethyl-1，7-dihydro-dipyrazolo[3，4-b；4’3’-e]pyridine)(PAP)及其组合之一，其中发蓝光的。绿光染料333可选择香豆素6(Coumarin 6)(C6)、香豆素545T(Coumarin 545T)(C545T)、三(8-羟基喹啉)铝(III)(tris(8-hydroxyquinolinato)aluminum(III)(Alq3)或dimethylquinacridones)(DMQA)及其组合的其中之一；且，该绿光染料333对该发光层33的容积比例范围是0.1％至20％之间。Wherein the light-emitting layer 33 can be selected from 1,4-bis(2,2-diphenylvinyl)benzene (1,4-bis(2,2-diphenyl vinyl)benzene) (DPVBi), diphenylethylene aromatic hydroxyl Derivatives (distyrylarylene(DSA))

(For example: the high-brightness blue light main material manufactured by Idemitsu Kosan Co., Ltd., the number is Ide120), bis(2-methyl-8-quinoline) 4-hydroxybiphenyl aluminum (bis(2-methyl-8- quinolinato) 4-phenylphenolate aluminum (Balq)), polyvinylcarbazole (Poly(N-vinylcarbazole)) (PVK) or 4-{4-[N-(1-naphthyl)-N-phenylaminophenyl ]}-1,7-diphenyl-3,5-dimethyl-1,7-dihydro-dipyrazolo[3,4-b; 4'3'-e]pyridine (4-{4 -[N-(1-naphthyl)-N-phenylaminophenyl]}-1,7-diphenyl-3,5-dimethyl-1,7-dihydro-dipyrazolo[3,4-b;4'3'-e]pyridine ) (PAP) and one of its combinations, of which blue light is emitted. Green light dye 333 can choose Coumarin 6 (Coumarin 6) (C6), Coumarin 545T (Coumarin 545T) (C545T), tris (8-hydroxyquinolinato) aluminum (III) (tris (8-hydroxyquinolinato) aluminum (III) one of (Alq3) or dimethylquinacridones) (DMQA) and combinations thereof; and, the volume ratio of the green dye 333 to the light-emitting layer 33 ranges from 0.1% to 20%.

Again, the hole blocking layer 34 can be selected from N-arylbenzimidazoles (N-arylbenzimidazoles) (TPBi), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ( 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) (BCP), bis (2-methyl-8-quinoline) 4-hydroxy biphenyl aluminum (bis (2-methyl-8- quinolinato)4-phenylphenolatealuminum) (Balq), 3-(4'-tert-butylphenyl)-4-phenyl-5-(4"-diphenyl)-1,2,4-triazole (3- (4'-tert-butylphenyl)-4-phenyl-5-(4"-biphenyl)-1,2,4-triazole)(TAZ) or 2-(4-diphenyl)-5-(4-tert Butylphenyl)-1,3,4-oxadiazole (2-(4-biphenylyl)-5-(4-tert-butylphenyl)1,3,4-oxadiazole) (PBD) and combinations thereof one. The red light dye 344 can be selected from 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethylpyrrolidinyl-9-enyl)-4H -pyran (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran)(DCJTB), 2-{2-[2- (1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H, 5H-pyrido[3,2,1-ij]quinolin-9-yl)(2-{ 2-[2-(1,1,7,7-Tetramethyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl))(PhDCJT) , 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (4-(dicyanomethylene)-2-methyl-6-(4 -dimethylaminostyry)-4H-pyran) (DCM) or 4-dicyanomethylene-2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ i,j]quinolazin-8-yl)vinyl]-4H-pyran(4-dicyanomethylene-2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ i, j]quinolizin-8-yl)vinyl]-4H-pyran)(DCM2) and one of its combinations; and, the volume ratio of the red dye 344 to the hole blocking layer 34 ranges from 0.1% to 5%.

Because the luminescent materials that emit red, green, and blue primary color light sources are all luminescent main materials, the concentration of dyes doped with various colors is relatively large, and there is a large tolerance for process stability errors. A slight concentration change will not cause obvious deviations in light color. , so that the difficulty of the process is reduced.

Please also refer to FIG. 5 , which is a schematic diagram of energy levels of each element in an embodiment of the device according to the present invention. Give an embodiment to illustrate effect of the present invention simultaneously, the structure of the present embodiment is as follows:

Hole transport layer 32 (BPAPF 600 angstroms)/luminescent layer 33 (PAP: 1.5% green dye 333 (Alq3 200 angstroms))/hole blocking layer 34 (TPBi: 0.8% red dye 344 (DCJTB 100 angstroms)) / electron transport layer 35 (Alq 200 angstroms) / electron injection layer 36 (LiF7 angstroms) / cathode 37 (Al 1500 angstroms).

The schematic diagram of the energy levels of its components is shown in Figure 5, where E _XC represents the energy level difference between the vacuum energy level and the conduction energy level of the XC component (X is the code name of the 31-37 component), which also represents the electron affinity of the component. ); E _XV represents the energy level difference between the vacuum energy level and the valence band energy level of the XV element (X is the code of the 31-37 element), which also represents the ionization potential of the element.

As shown in the figure, the greater the electron affinity E _XC and the smaller the energy gap between the two elements, the easier it is for electrons to be injected. Therefore, when the device is biased, electrons will pass through the electron transfer layer 35 from the cathode 37 to holes. The barrier layer 34 and the light-emitting layer 33, and because the conduction energy level _E33C of the light-emitting layer to the conduction energy level E32C of the hole transport layer ₃₂ is much larger than the former _E34C to _E33C , so electrons will jump over the light-emitting layer 33 to the hole The probability of the hole transport layer 32 is relatively small, so most of the injected electrons will stay in the hole blocking layer 34 and the light emitting layer 33 .

On the other hand, the holes injected into the hole transport layer 32 by the anode of the transparent conductive substrate 31 will enter the luminescence quickly from the hole transport layer 32 due to the orderly lowering of the valence band energy levels E _M31 , E _32V , and E _33V . layer 33, and because the energy level difference from the valence band energy level E _33V of the light-emitting layer 33 to the valence band energy level E _34V of the hole blocking layer 34 is extremely large, the holes will jump over the hole blocking layer 34 to the electron transport layer The probability of 35 is relatively small, so most of the injected holes will stay at the interface between the hole blocking layer 34 and the light-emitting layer 33, so that the two light-emitting layers participate in the light emission at the same time. Under different operating voltages, due to the structural design of the energy level difference, the recombination region of electrons and holes does not change, and remains at the interface of the two light-emitting layers.

Through the two light-emitting layers 33 with light-emitting function and the hole-blocking layer 34, there is an energy gradient design, so that when the device of the present invention emits colored light, the light wavelength corresponding to the luminous intensity will be compared as shown in Figure 6, which is a color of light. When the wavelength is 450-630nm, it is a full-wavelength white light emitting device with consistent intensity, and the light intensity within the wavelength of 450-630nm is maintained above 0.8, so that the three primary colors (light within the wavelength of 450-630nm) will be a uniform light intensity of each color. The full-wavelength white light organic electroluminescent device, as shown in Figure 7, the white light emitted by the present embodiment at voltages of 10, 11, 12, 13 and 14V is shown in the coordinate diagram of the chromaticity coordinate diagram (CIE). It is quite good white light, and the coordinates of the chromaticity coordinate diagram (CIE) in the operating practical area do not change greatly with the change of voltage, so the full-wavelength white light organic electroluminescent device of the present invention is very suitable for making with color filters Full color display.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims (8)

1. long white light organic electroluminescence device of all-wave is characterized in that the long white light organic electroluminescence device of described all-wave comprises:

One transparent conductive substrate (31);

One is arranged at the hole transport layer (32) on the described transparent conductive substrate (31);

One is arranged at the luminescent layer (33) on the described hole transport layer (32), and described luminescent layer (33) includes the blue light material of green glow dyestuff (333) by one and forms the luminescent layer (33) of the green light source of turning blue;

One is arranged at the hole barrier layer (34) on the described luminescent layer (33), and in described hole barrier layer (34) doping red dye (344), make described hole barrier layer (34) send red light source;

One is arranged at the electron transfer layer (35) on the described hole barrier layer (34);

One is arranged at the electron injecting layer (36) on the described electron transfer layer (35);

One is arranged at the negative electrode (37) on the described electron injecting layer (36).

2. the long white light organic electroluminescence device of all-wave according to claim 1 is characterized in that, described luminescent layer (33) selects 1, the derivative of 4-two (2, the 2-diphenylacetylene) benzene, talan fragrance hydroxyl

Two (2-methyl-8-quinoline) 4-Hydroxybiphenyl aluminium, Polyvinyl carbazole or 4-{4-[N-(1-naphthyl)-N-phenyl amino phenyl] }-1,7-diphenyl-3,5-dimethyl-1,7-dihydro-two pyrazolo [3,4-b; 4 ' 3 '-e] in pyridine and the combination thereof one of blue light-emitting, wherein n represents the number of Ar.

3. the long white light organic electroluminescence device of all-wave according to claim 1, it is characterized in that described green glow dyestuff (333) is selected one of them of coumarin 6, cumarin 545T, three (oxine) aluminium (III) or dimethylquinacridone and combination thereof.

4. the long white light organic electroluminescence device of all-wave according to claim 1 is characterized in that described green glow dyestuff (333) is between 0.1% to 20% to the volume proportion of described luminescent layer (33).

5. the long white light organic electroluminescence device of all-wave according to claim 1, it is characterized in that, described hole barrier layer (34) is selected N-aryl benzimidazole, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, two (2-methyl-8-quinoline) 4-Hydroxybiphenyl aluminium, 3-(4 '-tert-butyl-phenyl)-4-phenyl-5-(4 "-diphenyl)-1; 2; 4-triazole or 2-(4-diphenyl)-5-(4-tert-butyl-phenyl)-1,3, one of them of 4-oxadiazole and combination thereof.

6. the long white light organic electroluminescence device of all-wave according to claim 1, it is characterized in that described red dye (344) is selected 4-(dicyano the methylene)-2-tert-butyl group-6-(1,1,7, the 7-tetramethyl is coughed up Ding Ji-9-thiazolinyl for a long time)-the 4H-pyrans, 2-{2-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydrochysene-1H, 5H-pyrido [3,2,1-ij] quinoline-9-yl), 4-(dicyano methylene)-2-methyl-6-(4-dimethylamino styryl)-4H-pyrans or 4-dicyano methylene-2-methyl-6-[2-(2,3,6,7-tetrahydrochysene-1H, 5H-benzo [i, j] quinolizine-8-yl) vinyl]-one of them of 4H-pyrans and combination thereof.

7. the long white light organic electroluminescence device of all-wave according to claim 1, wherein, described red dye (344) is between 0.1% to 5% to the volume proportion of described hole barrier layer (34).

8. the manufacture method of the long white light organic electroluminescence device of all-wave, the structure of the long white light organic electroluminescence device of described all-wave are to be provided with hole transport layer (32), luminescent layer (33), hole barrier layer (34), electron transfer layer (35), and electron injecting layer (36) between a corresponding transparent conductive substrate as anode (31) and negative electrode (37);

It is characterized in that:

Described luminescent layer (33) is the luminescent layer (33) that is formed the green light source of turning blue by a blue light material that includes the green glow dyestuff (333) that is all luminous material of main part;

The red dye (344) of doping one luminous material of main part in the described hole barrier layer (34), making hole barrier layer (34) is the hole barrier layer (34) that sends red light source;

The white light source that is combined into by described bluish-green light source and red light source.

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